Modern communication systems typically use electromagnetic signals to carry information. These electromagnetic signals may be in the form of voltages and currents carried by wires or cables, or in the form of electromagnetic fields such as radio waves, microwaves, infrared signals, light, etc. transmitted through space, transmission lines, or waveguides. While electromagnetic signals provide a good physical layer for carrying information in many cases, they are not without shortcomings.
When devices that need to communicate are in fixed positions relative to one another, conductors are often used to convey information between the devices. For example, in a vehicle, numerous sensors and various system modules, such as the Engine Control Unit (ECU), may be connected through a wiring harness comprising a plurality of wires and/or cables. Cables may have certain advantages such as consistency of the connection, but they can also have certain drawbacks. For example, vehicular cables are bulky and heavy, and add significantly to the total weight of a modern automobile. Cables are also prone to external attacks such as tapping, which compromises the security of not only the data carried by the cables, but also the vehicle and its occupants since the information carried by the cables can be critical to operation of the vehicle. Cables can also degrade over time by flexing and/or exposure to the elements.
One way to reduce the use of cables is by transmitting data wirelessly using radio waves. Moving at least some of the wired communication to a wireless system that communicates using radio waves has the potential to reduce the number and weight of vehicular cables. Radio waves commonly refer to electromagnetic signals having frequencies that lie in a range of frequencies extending from around 3 kHz to 300 GHz. To transmit data using radio waves, a communication protocol must be used to encode the data so that it can be carried by the radio waves. The transmitted data is then recovered by decoding the data at the receiving end.
Two commonly used wireless communication protocols that use radio waves to transport information include Bluetooth®, which is a communications protocol maintained by the Bluetooth Special Interest Group (SIG) of Kirkland, Washingtion, and ZigBee®, which is an IEEE 802.15.4-based communication protocol maintained by the ZigBee Alliance of Davis, Calif. Both these protocols are standards for exchanging data over short distances using Ultra High Frequency (UHF) radio waves in the Industrial, Scientific and Medical (ISM) 2.4 GHz radio frequency band. Though both Bluetooth and Zigbee are capable of providing reliable high-speed communication, they also have shortcomings.
For example, devices communicating over Bluetooth must be “paired”, or synchronized each time they are powered up, which takes a considerable amount of time. Zigbee uses the same frequency band as Wi-Fi®, which is communications protocol based on the IEEE 802.11 standards that is maintained by the Wi-Fi Alliance of Austin, Tex. When both Zigbee and Wi-Fi signals use the channel at the same time, it can create interference that causes a loss of data. Moreover, available radio spectrum is already congested, so using radio waves to replace cables in vehicles only adds to this congestion. The problems of radio spectrum congestion thus reduces the viability of radio waves as a replacement for cables in vehicles. In addition, wireless communication protocols transmitted using radio waves often have significant security issues, and may be vulnerable to jamming attacks.
Jamming attacks are denial-of-service attacks in which the attacker corrupts the content of a transmitted message by transmitting malicious radio frequency signals that corrupt or block the message. An attacker may jam a Bluetooth or Zigbee signal from outside a vehicle or building by transmitting interfering signals at the same frequency. Thus, even if the other problems associated with synchronization and congestion could be overcome, radio frequency-based communications protocols would still have significant security issues, and thus may be unsuitable replacements for cables.
Another environment that often uses wireless communication protocols are public areas such as airports, supermarkets, hospitals, sports venues, etc. Typically, these areas include one or more public and or private communication networks, such as Wi-Fi, cellular, cordless phones, two-way radios, etc. These communication networks are often provided or enhanced using access points and/or repeater systems that operate in the same frequency bands. When coupled with the high concentrations of devices often found in these crowded areas, interference and congestion can result.
Thus, there is a need for improved systems, methods, and computer program products which enable the transmission of data between devices and secure transmission of information to selected devices, individuals, or groups in public areas.